Scientists at P&S have confirmed the validity of a gene associated
with prostate cancer and its potential use as the basis for earlier
detection and staging methods for the disease. The confirmation was
published in the January issue of Cancer Research.

The new gene, known as PTI-1, was first identified in 1995
by principal investigator Dr. Paul B. Fisher, professor of clinical
pathology in pathology and urology, and colleagues.

In this study, Dr. Fisher's research team found that PTI-1
can detect a single prostate cancer cell in 100 million normal cells,
indicating that the gene is an extremely sensitive detector of
prostate cancer. Analysis of RNA from 30 blood samples used in the
study indicates PTI-1 is expressed in patients with prostate cancer
that has spread outside the gland, but not in patients without
prostate cancer or those whose cancer is confined to the prostate.
The findings have important implications because current methods
for detecting prostate cancer cannot easily differentiate between
prostate cancers confined to the prostate gland and those with
metastatic potential. Serum prostate-specific antigen (PSA) and
RT-PCR of PSA determinations detect both malignant and benign
prostate disease; physical examination may miss small or centrally
located tumors; and sampling error in tissue biopsy may lead to
erroneous benign diagnosis.

"Although further testing with a larger number of patient
samples is clearly needed, these provocative results suggest that
PTI-1 monitoring might prove beneficial in prostate cancer
diagnosis and provide an extremely sensitive marker for prostate
cancer progression," the authors wrote.

The technique used to find the PTI-1 gene is known as rapid
expression cloning and may represent an important advance for attempts
to identify oncogenes in a wide variety of human cancers. Columbia
University has licensed the technology to GenQuest (Seattle and New
York City), a genomics company formed to focus on the identification
and characterization of cancer-related genes. A patent application
has been filed for the PTI-1 gene.

The research was funded by the Association for the Cure of
Cancer of the Prostate; the Samuel Waxman Cancer Foundation; and
the Chernow Endowment, of which Dr. Fisher is the Chernow Research
Scientist. Other members of the research team were Drs. Yilong Sun,
Jian Lin, and Aaron E. Katz.